Chuck,
the most significant modification - the IF-amplifier buffer and AF-amplifier
circuit.
The first mod helps to provide much smaller own noise level for K3 (10dB
down !!!),
and second mod takes more realistic sound.
We talks about it earlier in the thread:
http://mailman.qth.net/pipermail/elecraft/2009-June/111985.html
The mods for 1-st and 2-nd mixer can be helpful only for multi-TX
high-power contest station.
In any event, all pictures of these mods here:
http://ur5lam.jimdo.com/elecraft-k3-mod-s-page/
if you want to see the big photos, you find and download it here:
http://forum.cqham.ru/viewtopic.php?t=17137&postdays=0&postorder=asc&&start=870
http://forum.cqham.ru/viewtopic.php?t=17137&postdays=0&postorder=asc&&start=900
All of these mods are not difficult. But results is very nice.
My K3 has much poor sound in A/B comparison with my small K2.
But now, I have the new Radio, really excellent receiver and beautiful sound
after mods.
I can hear the difference by my ear, I can see the difference by my eyes on
the comparison plots.
FW last beta 3.30
73! GL!
Alex UR5LAM
2009/9/27 Chuck - AE4CW
>
> Alex,
>
> Can you please be specific about which HW mods you installed? Are they all
> published by Elecraft? I don't recall any 1st and 2nd Mixer mods being
> published. If not, can you please share them?
>
> Are the software mods in the current beta FW, i.e. 3.30?
>
> Thanks.
>
> Chuck, AE4CW
>
>
>
> Alexander Ponomarenko-5 wrote:
> >
> > Today we finished our K3 IMD-test in our home-laboratory. :)
> > We has the nice results I think.
> > Same improvements we have after modifications in hardware (mods for 1st
> > and 2nd Mixer, IF-buffer and AF-amplifier).
> > Same improvements we have after excellent software "AGC-mods" from Lyle
> > Johnson.
> > And here is the nice result in total.
> >
> > 2-tone-IMD-Plot for K3/100F BEFORE mods:
> > http://forum.cqham.ru/download.php?id=48688
> > here we can see very dirty and nonlinear signal
> >
> > Plot for K3/100F AFTER hardware mods:
> > http://forum.cqham.ru/download.php?id=48689
> > more clean and linear signal
> >
> > Plot for K3/100F AFTER hardware mods AND new AGC:
> > http://forum.cqham.ru/download.php?id=48677
> > and nice result in total.
> >
> > GL! 73!
> > Alex UR5LAM
>
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